Your brain controls everything you do. It makes it_________for you to think, learn, create and feel; to blink（眨眼） and breathe and for your heart to beat—this fantastic control center is your________ .
Can this small grey organ（器官）, which _________ less than one and a half kilos, really do so much? Amazingly, your brain contains about 100 billion neurons（神经元）—it would _________you over 3,000 years to count them all. Believe it or not, the ________ in your brain never stops. Your neurons create and send more messages than all the phones in the world. And although one neuron_________only a little electricity, all your neurons together can _______ enough electricity to supply a light bulb（灯泡）.
So exactly how fast does your brain work? Well, imagine this: A bee lands on your foot. Neurons in your skin send this information to your brain_________a speed of more than 240 kilometers per hour. Your brain then uses _________ neurons to send the message back to your foot to shake the bee off ________. These neurons can send this__________at more than 320 kilometers per hour. No computer has your brain’s unbelievable ability to deal with the amount of information coming from your eyes, ears and other sensory organs.
But how does your brain allow you________ things that you will use in the future? The structure（ 结 构 ）of your brain changes every time you have a new_________, remember or learn something. For example, riding a bike seems impossible at first, _________ soon you are able to do it. How? As you practice, your brain ________“bike riding” messages again and again. Soon, the actions are learned and you are able to ride a bike easily from then on.
1.A.possible B.impossible C.polite D.impolite
2.A.mouth B.brain C.eye D.heart
3.A.works B.takes C.weighs D.grows
4.A.take B.cost C.spend D.pay
5.A.action B.electricity C.breath D.activity
6.A.creates B.invents C.discovers D.finds
7.A.provide B.protect C.produce D.become
8.A.in B.at C.with D.for
9.A.other B.another C.the other D.others
10.A.quickly B.quietly C.probably D.carefully
11.A.news B.product C.information D.purpose
12.A.to think B.to learn C.to use D.to change
13.A.mind B.sense C.feeling D.thought
14.A.so B.because C.and D.but
15.A.offers B.takes C.sends D.leaves